Background: Ischemic heart disease is the major cause of morbidity and mortality. The diagnosis of chronic coronary syndrome is a challenge as most of the diagnostic investigation are either invasive or involve radiation or contrast material. The aim of our study was to find a scoring system comprising diagnostic parameters which are non-invasive and involve minimal radiation or contrast material and yet have high diagnostic yield. Methods: In this non-randomized study conducted at KRL hospital Islamabad from Oct 2022 to Aug 2024, we took baseline characteristics and calculated Non Invasive, Minimal Radiation score (NIMR score) comprising risk factors, ETT, coronary calcium score and age of the patients, aged 18 and above. They then underwent CCTA to look for CAD. The association of the CAD with the score was checked using regression analysis on IBM SPSS version 26. Results: Out of total 150 participants, 60% were male, mean age with SD was 50.54±7.82 and age ranged from 40-67 years. CAD was more prevalent in male and increased with increasing age. On Univariate analysis, NIMR score both as continuous variable and as categorical variable emerged as strong predictor of CAD (OR: 2.45, 95% CI: 1.84-3.25, pValue: 0.000) and (OR: 64.09, 95% CI: 14.53-282.74, pValue: 0.000) respectively. On multivariate analysis also the NIMR score was strong predictor of CAD both as continuous variable (OR: 2.43, 95%CI: 1.83-3.24, pValue: 0.000) and as categorical variable (OR: 67.11, 95%CI: 14.47-311.14, pValue: 0.000). Conclusion: In conclusion, NIMR score, which is non-invasive, with minimal radiation and no contrast material involvement is a strong predictor of CAD in low and intermediate risk patients and very applicable in day to day clinical practice. KEY WORDS: NIMR score, Ischemic heart disease, Coronary Artery Calcium Score, CT coronary angiography, Invasive Coronary Angiography, Radiation, SPECT MPI, PET scan, Exercise Tolerance Test

The authors have declared no competing interest.

No funding involved

I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.

Yes

The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

Ref ERC: KRL-HI-PUB-ERC/Oct22/19 Ethical Review committee of KRL Hospital Islamabad has thorougly reviewed the study of Dr Ibrahim Gul of this hospital Titled :INCORPORATION OF NON-INVASIVE, CONTRAST-FREE, AND MINIMAL RADIATION PARAMETERS IN THE DIAGNOSTIC MODALITIES OF CORONARY ARTERY DISEASE" which he will conduct in KRL hospital Islamabad. The committee did not find anything in this study which is unethical, injurious or against the international guidelines for biomedical research involving human or animal subjects.

I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals.

Yes

I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance).

Yes

I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable.

Yes

All the data will be made available if and when required